This invention relates to jigsaws or scroll saws which have a saw blade connected between the free ends of the arms of a generally C-shaped or U-shaped member which is reciprocated about a pivot point at the closed end of the member to drive the saw blade. Means are provided to quickly connect or disconnect the saw blade between the ends of the arms. Typically, at least one end of the saw blade is clamped between a pair of blade holders, an example of which is shown in FIG. 6 of the Sutton U.S. Pat. No. 4,503,742, issued Mar. 12, 1985. It is difficult to adjust the tension on the blade by using such blade holders, but if the blade is not correctly tensioned it may tend to break upon encountering a workpiece.
An example of a releaseable prior art blade tensioning device is disclosed in the Dremel U.S. Pat. No. 2,721,587, issued Oct. 25, 1955. The Dremel jigsaw has a pivotable blade holder attached to the end of the upper arm which can be pivoted between blade tightening and blade releasing positions. In the blade tightening position, a lever can be pivoted into position to lock the blade carrier in place, with the blade under tension. However, no means are provided to readily adjust the amount of tension being applied to the blade.